Certain languages, for example Clojure, Common Lisp, or Cython, are dynamically
typed by default, but allow this behaviour to be overridden through the use of
explicit type hints that result in static typing.
One reason to use such hints would be to achieve the performance benefits
of static typing in performance-sensitive parts of code.

So, to get close to (statically typed) Java in terms of speed,
Perl 5 would need to make significant tweaks to its type system
and the way it handles polymorphism, as indicated by chromatic's response.
See also MJD perl.com article (2001),
which explains why making Perl as fast as C is problematic.